Amps
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Re: [Amps] HB amps

To: "'Ian White GM3SEK'" <gm3sek@ifwtech.co.uk>,<amps@contesting.com>
Subject: Re: [Amps] HB amps
From: "Gary Schafer" <garyschafer@comcast.net>
Reply-to: garyschafer@comcast.net
Date: Fri, 3 Mar 2006 17:39:39 -0500
List-post: <mailto:amps@contesting.com>

> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Ian White GM3SEK
> Sent: Friday, March 03, 2006 2:45 PM
> To: amps@contesting.com
> Subject: Re: [Amps] HB amps
> 
> Gary Schafer wrote:
> >>
> >> An 813 only has 125W dissipation, so by today's standards they are
> small
> >> tubes. You'd need four to equal a single 3-500Z, which will glow just
> as
> >> nicely.
> >>
> >> A pair would be struggling to reach even the "1kW input class", and the
> >> clean linear output is unlikely to be more than 400W. Even if you have
> a
> >> box full of 813s, is it worth the effort of building such a small amp?
> >>
> >>
> >>
> >> --
> >> 73 from Ian GM3SEK
> >
> >A pair of 813's will easily produce 600 watts output and do it for years
> and
> >years. They are very rugged tubes. I have an amp with a pair of them that
> I
> >built in the mid 60's and it still has the same pair of tubes. At one
> time I
> >ran them with over 3000 volts on the plates for several years with the
> >plates regularly showing color and power out well above 600 watts.
> >The same tubes now run at around 2500 volts and still put out 600 watts
> and
> >no color.
> >
> >Not the best tube in the world but for the price and as rugged as they
> are
> >they are hard to beat.
> >They will perform well on a wide range of voltages too. 2000 to 3000
> volts.
> >
> 
> I don't dispute the raw output figures, or the ruggedness either; but
> you didn't address my point about "clean, linear output". How do the IMD
> levels at 600W output compare with a 3-500Z?
> 
> 
> --
> 73 from Ian GM3SEK

It has been many years since I looked at the IMD on them but remember that
it was not real terrible.

73
Gary  K4FMX


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